It is often necessary to pass an optical fiber through a wall, such as the wall of a vessel or package containing electronic components. When the wall separates two regions with significantly different pressure, such as an evacuated region or the inside of a vessel, from the atmosphere, the fiber needs to pass through the wall without allowing gas leakage. Traditional methods involve stripping off a portion of the fiber cladding in the region of the fiber that passes through the wall, filling in the stripped portion with an epoxy layer, and positioning and sealing the epoxy-coated portion in an aperture passing through the wall. In order to provide a good hermetic seal a tight mechanical attachment is usually required. But such a tight attachment tends to induce stress on the optical fiber, and this stress can degrade the quality of the fiber transmission through the wall. In particular, the stress can degrade the polarization extinction ratio (PER).